The present invention relates to a semiconductor device and a manufacturing method of the semiconductor device, and more particularly, to a semiconductor device manufactured with the use of the laser welding technique and a manufacturing method of the semiconductor device.
As a power converter, such as an industrial converter, a semiconductor device incorporating a semiconductor element, such as an IGBT (Insulated Gate Bipolar Transistor), has been used (for example, see JP-A-2005-116702). FIG. 16 is a schematic cross section of the major portion of a semiconductor device. In a semiconductor device 100, a Cu (copper) base 102 is joined to the bottom of an insulating substrate 101 via a solder 103, and a resin case 105 molded to enclose an IGBT element 104 is bonded to the Cu (copper) base 102 along the upper edge 102a thereof.
An emitter terminal 106 and a collector terminal 107 serving as external connection terminals are provided to the inner wall of the resin case 105, and electrically connected to a circuit pattern 110 formed by the DCB (Direct Copper Bonding) method on the insulating substrate 101 via plural aluminum wires 108 and 109, respectively.
Although it is not shown in the drawing, the surface electrode of the IGBT element 104 is formed by aluminum (Al) deposition. However, because Au-plating processing is applied onto the uppermost surface, solder joining is enabled. A heat spreader 111 is joined to the surface electrode positioned on the top surface of the IGBT element 104 via a solder 112. In other words, the heat spreader 111 is connected to an emitter electrode formed on the surface of the IGBT element 104. One ends of aluminum wires 113 are attached to the top surface of the heat spreader 111 by bonding, and the other ends thereof are connected to the circuit pattern 110 formed on the insulating substrate 101. An emitter current thus flows into the circuit pattern 110 from the heat spreader 111 via the aluminum wires 113.
A collector electrode is formed on the bottom surface of the IGBT element 104 and connected to the circuit pattern 110 on the insulating substrate 101 via a solder 114. Although it is not shown in the drawing, a gate electrode is also formed on the surface of the IGBT element 104, and an aluminum wire 115a to electrically connect the gate electrode to the circuit pattern 110 is attached to the gate electrode by bonding. Further, an aluminum wire 115b extends from a portion corresponding to the circuit pattern 110 that is electrically connected to the gate electrode, and the tip end thereof is connected to an unillustrated gate terminal provided to the inner wall of the resin case 105.
Furthermore, in order to protect the IGBT element 104 and other elements inside the resin case 105 from moisture, humidity, dust, and so forth, the inside of the resin case 105 is encapsulated with gel 116.
As has been described, bonding using the wires is performed to ensure electrical connections among respective portions in the semiconductor device 100 incorporating the IGBT element 104 and the like.
In the semiconductor device 100 as is shown in FIG. 16, because the emitter current and the collector current have a large current capacity, it is necessary to increase the number of aluminum wires 108, 109, and 113 for the currents of a large capacity to flow at a time. However, because individual wires have to be welded one by one, there arises a problem that the manufacturing process takes too long a time.
In addition, in order to achieve downsizing and greater packaging density, respective members forming a semiconductor device are disposed intricately in a semiconductor device in recent years. Moreover, because the number of wires increases with an increase in capacity of the semiconductor device, there is another problem that it takes considerable time and labor until the bonding of all the wires is completed.